Help me troubleshoot. Brake booster or MC?
Thread Starter
college kid
Joined: Mar 2003
Posts: 2,000
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From: New York
Help me troubleshoot. Brake booster or MC?
Looking for help troubleshooting which part is faulty here.
Car is a 97 civic dx. already swapped on 10.3" and milled ITR calipers up front a few months back. Just did a GSR rear disk swap, started to bleed the system then decided i better swap in my new MC and booster. 1" gsr MC and booster from a 94-97 integra gsr ABS model. (does abs vs non-abs matter?).
i do the booster/MC swap, run new lines to the mc and bench bleed the MC. Now, bleeding the calipers in the proper sequence starting at RIGHT REAR. bleed it out like 15 times bubbles here and there then no more bubbles on the last 5 bleeds. good, so i move to the FRONT LEFT. bleed out bubbles on the first few, then no more bubbles on the next bunch.
HERE"S THE IMPORTANT PART
Then i move to the LEFT REAR. my dad says "hm your pedal is WAY at the very top". he holds the pedal and tells me to open the bleeder. i open the bleeder 1/4 turn and he says "the pedal is not going down at all?". i close the bleeder we try again. same thing pedal doesn't go down. then we hear a loud POP and the pedal falls pretty easily to the floor. i close the bleeder and we try to maybe bleed it again. this time the pedal sinks fast and practically no fluid or air comes out the bleeder valve on the caliper. try two more times nothing. theres no pressure getting to the back.
I test the pedal out myself and theres a bit of resistance on the pedal, it does always come back up to the top, but you can still easily hit it to the floor.
Today i read Helms and Haynes and did some tests on the booster:
--I checked the booster vacuum line by removing it from the booster and starting the engine. the line has PLENTY of vacuum so it seems the check-valve booster line is good.
--i held the brake pedal and started the car and the pedal did sink a little. but it was also VERY VERY easy to put the pedal to the floor.
--i turned the car off and pumped the pedal a few times, it would build up to the VERY top. so basically there was no travel in the pedal at all. if i hold moderate pressure on the pedal, it did seem like it would eventually sink down a bit.
--I visually checked MC, Propvalve and four calipers, i'm not leaking any fluids and the resevior level has not gone down.
SORRY FOR THE LONG STORY.
What do you guys think is the problem? Bad MC or bad booster?
Thank you!!!
-Luke
Car is a 97 civic dx. already swapped on 10.3" and milled ITR calipers up front a few months back. Just did a GSR rear disk swap, started to bleed the system then decided i better swap in my new MC and booster. 1" gsr MC and booster from a 94-97 integra gsr ABS model. (does abs vs non-abs matter?).
i do the booster/MC swap, run new lines to the mc and bench bleed the MC. Now, bleeding the calipers in the proper sequence starting at RIGHT REAR. bleed it out like 15 times bubbles here and there then no more bubbles on the last 5 bleeds. good, so i move to the FRONT LEFT. bleed out bubbles on the first few, then no more bubbles on the next bunch.
HERE"S THE IMPORTANT PART
Then i move to the LEFT REAR. my dad says "hm your pedal is WAY at the very top". he holds the pedal and tells me to open the bleeder. i open the bleeder 1/4 turn and he says "the pedal is not going down at all?". i close the bleeder we try again. same thing pedal doesn't go down. then we hear a loud POP and the pedal falls pretty easily to the floor. i close the bleeder and we try to maybe bleed it again. this time the pedal sinks fast and practically no fluid or air comes out the bleeder valve on the caliper. try two more times nothing. theres no pressure getting to the back.
I test the pedal out myself and theres a bit of resistance on the pedal, it does always come back up to the top, but you can still easily hit it to the floor.
Today i read Helms and Haynes and did some tests on the booster:
--I checked the booster vacuum line by removing it from the booster and starting the engine. the line has PLENTY of vacuum so it seems the check-valve booster line is good.
--i held the brake pedal and started the car and the pedal did sink a little. but it was also VERY VERY easy to put the pedal to the floor.
--i turned the car off and pumped the pedal a few times, it would build up to the VERY top. so basically there was no travel in the pedal at all. if i hold moderate pressure on the pedal, it did seem like it would eventually sink down a bit.
--I visually checked MC, Propvalve and four calipers, i'm not leaking any fluids and the resevior level has not gone down.
SORRY FOR THE LONG STORY.
What do you guys think is the problem? Bad MC or bad booster?
Thank you!!!
-Luke
Thread Starter
college kid
Joined: Mar 2003
Posts: 2,000
Likes: 0
From: New York
UPDATE: I removed the master cylinder and bench bled it again. after a few pumps (6 or 7) the lines were clear of bubbles. its not leaking anywhere. and both ports seem to be pumping out the same amount of fluids. anything else i should do with the MC to test its functionality? block off the ports and push the rod to see if its bypassing internally?
-Luke
-Luke
Thread Starter
college kid
Joined: Mar 2003
Posts: 2,000
Likes: 0
From: New York
HAN is a great forum..lol just not for brake questions.
well here is the rest of the story incase anyone stumbles across this
OK. rebench bled the MC. with a better setup that did not allow any air back in. i realize now the old bench bleed setup did allow the suction of a few air bubbles back into one port on the MC.
-regreased the piston on the MC, the seal, and the rod on the booster
-reinstalled it on the booster. double checked torque specs for MC-booster
-cleaned out the resevoir basket (it now had rusty particles inside the basket. ??) topped off fluid.
to eliminate any chance of somehow super offsetting the chambers of the mc we only bled each caliper about 5 times. last time we started off fully bleeding the line (15-20 on the rear). we successfully did the RR, and then the left front again. now we were at the left rear. the same place it went POP last time. we start off bleeding and have LOW pressure. hardly much coming out the bleed line. on the 3rd bleed i feel a big wiggle in the bleed line and then BAM we have full pressure again!! bleed about 3 more times. good solid pressure.
we finish the sequence. top off the fluids again and went all the way around successfully a second time, still only bleeding about 6 times on each caliper. i think i might run the engine and see what i feel. if all is well i'll do a full bleed.
well.. bled the car until there was nothing but brand new clear fluid coming out the end. kept testing the brakes with the engine on and off. pedal felt normal. but possibly a bit low and still perhaps a bit squishy. not sure if i'm paranoid now or what.
dropped the car off the blocks and took it around the blocks and parking lots. i don't know what else to say but... it works? brakes are working, ebrakes are working (might need a bit more tightening) but all in all...everything seems to be working? the pedal may be a bit low and squishy. could this be attributed to shitty ass old rusty rotors in the back? i used the ones that came with the swap.
as you can tell i'm still cautious about it all. i'll do nothing but drive it around just the closest blocks before i have full faith in the brakes.
One of the good things that always comes about when i do a project: i make a writeup
"How to Swap your Brake Master Cylinder and brake booster"
http://www.lukekailburn.com/boostermc.html
-Luke
well here is the rest of the story incase anyone stumbles across this
OK. rebench bled the MC. with a better setup that did not allow any air back in. i realize now the old bench bleed setup did allow the suction of a few air bubbles back into one port on the MC.
-regreased the piston on the MC, the seal, and the rod on the booster
-reinstalled it on the booster. double checked torque specs for MC-booster
-cleaned out the resevoir basket (it now had rusty particles inside the basket. ??) topped off fluid.
to eliminate any chance of somehow super offsetting the chambers of the mc we only bled each caliper about 5 times. last time we started off fully bleeding the line (15-20 on the rear). we successfully did the RR, and then the left front again. now we were at the left rear. the same place it went POP last time. we start off bleeding and have LOW pressure. hardly much coming out the bleed line. on the 3rd bleed i feel a big wiggle in the bleed line and then BAM we have full pressure again!! bleed about 3 more times. good solid pressure.
we finish the sequence. top off the fluids again and went all the way around successfully a second time, still only bleeding about 6 times on each caliper. i think i might run the engine and see what i feel. if all is well i'll do a full bleed.
well.. bled the car until there was nothing but brand new clear fluid coming out the end. kept testing the brakes with the engine on and off. pedal felt normal. but possibly a bit low and still perhaps a bit squishy. not sure if i'm paranoid now or what.
dropped the car off the blocks and took it around the blocks and parking lots. i don't know what else to say but... it works? brakes are working, ebrakes are working (might need a bit more tightening) but all in all...everything seems to be working? the pedal may be a bit low and squishy. could this be attributed to shitty ass old rusty rotors in the back? i used the ones that came with the swap.
as you can tell i'm still cautious about it all. i'll do nothing but drive it around just the closest blocks before i have full faith in the brakes.
One of the good things that always comes about when i do a project: i make a writeup
"How to Swap your Brake Master Cylinder and brake booster"
http://www.lukekailburn.com/boostermc.html
-Luke
v-card member alpha
Joined: Oct 2006
Posts: 4,010
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From: Assplosion, NE
Glad you got it worked out :goodjob:
My brake pedal is a bit low and squishy compared to most cars I've driven in the past (including the other Hondas) so maybe it's just the car or maybe it's that I, like you, have really old calipers in the rear (and in the front in my case).
I've done the various tests on mine as well and all seems to perform properly. Flushing the fluid did help, but the pedal still has a bit of travel before you really begin to brake. I thought for sure that putting new pads on front and rear would help but it didn't, though sometimes the pedal seems a bit lower than others :dunno:
My brake pedal is a bit low and squishy compared to most cars I've driven in the past (including the other Hondas) so maybe it's just the car or maybe it's that I, like you, have really old calipers in the rear (and in the front in my case).
I've done the various tests on mine as well and all seems to perform properly. Flushing the fluid did help, but the pedal still has a bit of travel before you really begin to brake. I thought for sure that putting new pads on front and rear would help but it didn't, though sometimes the pedal seems a bit lower than others :dunno:
Member
Joined: Sep 2008
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it was me...y? u gotta problem with that? im searching for brake master cylinder and brake booster problem and i found this shyt...and of course it helps to make my problem solved...i dont really want to start another thread and not getting any answers and shyt....so, i think its better to search it 1st then if i can't find anything, then fuck start a fresh fcking thread
Joined: Jul 2003
Posts: 28,282
Likes: 0
From: michigan
it was me...y? u gotta problem with that? im searching for brake master cylinder and brake booster problem and i found this shyt...and of course it helps to make my problem solved...i dont really want to start another thread and not getting any answers and shyt....so, i think its better to search it 1st then if i can't find anything, then fuck start a fresh fcking thread